The present invention relates to methods for removing dirt and other unwanted residues from produce, e.g., fruits and vegetables, which is intended for ingestion by humans or lower animals and to detersive compositions, especially in liquid form, which are especially suitable for practicing said methods.
It is well-known and appreciated by consumers that fruits and vegetables should be thoroughly washed prior to ingestion in order to remove soils and other unwanted residues which may be undesirably clinging to the surfaces thereof. In addition, some consumers wish to remove the artificial xe2x80x9cwaxyxe2x80x9d coatings which may be applied to some fruits to retard moisture loss for increased storage life and to enhance their appearance. It has been estimated that 95% of consumers recognize the need for thorough washing but, ordinarily, only use tap water for this purpose. On the order of 5% of those consumers who do wash their vegetables use a household cleaner, typically a liquid dishwashing product, to help ensure cleanliness. However, dishwashing products are not specifically intended for such use, inasmuch as they are usually designed to provide high, persistent suds which makes them inconvenient to remove from the fruits or vegetables which have been washed therewith. It will also be appreciated that the formulation of truly effective compositions, especially those which can be used safely by individual consumers, for washing fruits and vegetables presents a unique problem to the formulator, inasmuch as many art-disclosed cleaning ingredients would, presumably, not be desirable for use in direct contact with foods where they might not be fully removed.
Moreover, it would be especially desirable to provide effective, toxicologically-acceptable cleaning compositions for fruits and vegetables in the form of substantially low-sudsing liquid solutions which are clear or which have only minimal haziness. Liquid solutions are convenient for the user, since they can be applied directly to soiled fruits and vegetables, followed by rinsing in tap water. The clarity of the liquids connotes cleanliness to the user and is thus highly desirable. Low sudsing is an important attribute so that removal of the solution by rinsing is achieved quickly and easily. It would also be of advantage if such compositions could be provided in the form of concentrates, which could be diluted by the consumer before use and/or applied to the fruits and vegetables as a direct spray-on.
Unfortunately, many toxicologically-acceptable cleaning ingredients do not meet the aforesaid requirements for clear, low-sudsing, dilutable liquid products. Many detersive surfactants form cloudy or even opaque suspensions, even in soft water. Of course, many surfactants are specifically designed to be high sudsing. Still others form relatively intractable phases in their concentrated form.
It has been disclosed that soap and/or certain nonionic surfactants, properly formulated, e.g., with water-soluble oleate or laurate salts and other ingredients can provide liquid compositions having the desired properties described above. It has also been disclosed that preferred compositions can be formulated in the basic pH range. Even when such basic compositions do have a soapy feel, they are preferred over the acidic compositions herein for removing artificial waxy coatings, especially from fruit such as apples. However, the invention also comprises basic compositions having less soapy feel. It has now been discovered that the addition of neutralized phosphoric acid provides even better cleaning, especially of waxy material, even at the same pH.
The use and selection of cleaning ingredients for the purpose of washing fruits and vegetables is described by the United States Code of Federal Regulations, Title 21, Section 173.315: xe2x80x9cIngredients for use in washing or lye peeling of fruits and vegetablesxe2x80x9d. These regulations restrict the ingredients that may be used for direct contact with food to those described as xe2x80x9cgenerally regarded as safexe2x80x9d (GRAS), and a few other selected ingredients. These sections also provide certain limitations on the amount of material that can be used in a given context.
Among these ingredients, the experienced formulator will find only a few ingredients which can provide effective cleaning of hydrophobic residues, such as waxes, oils, or man-made chemical residues such as pesticides. It is recognized these types of residues are removed most readily by surface active ingredients in water, or by organic solvents largely in the absence of water. Other types of soils, especially particulate insoluble soils that do not readily disperse in water, are effectively removed by surface active materials in water, especially when aided by complex anionic salts, such as citrates (polycarboxylates), or polyphosphate salts.
Within this limited group of ingredients the range of effective cleaning compositions well suited to the task of cleaning fruits and vegetables, especially as practiced by individual consumers, have not been previously described. It is desirable to formulate liquid compositions which are amenable to either direct application to produce, preferably by spray application, or could be provided in suitable concentrated form to allow convenient dilution in a bowl or sink of water for washing of produce by immersion. Further, it is desirable if the compositions are low sudsing, and easily rinsed, without leaving residue. Preferred compositions should be mild to the hands, especially for direct application.
Food Chemical News, Inc., 1991, p. 334.1, reports that PEG 200-9500 has been cleared under xc2xa7178.3750 as a component in articles for use in contact with food (Fed. Register, Oct. 15, 1968). Nonetheless, for washing produce, polyethylene glycol should be affirmed as GRAS.
The present invention encompasses methods for cleaning produce, especially fruits and vegetables, (and compositions, as disclosed hereinafter, for practicing said methods) at a basic pH. The present invention comprises several aspects including:
I. A method for cleaning produce comprising contacting the surfaces of said produce by direct application of an aqueous cleaning solution typically comprising:
(a) from about 0.01% to about 15% of C8-C18 fatty acid;
(b) optionally, from about 0.1% to about 4% by weight of nonionic surfactant, especially ethoxylated and/or propoxylated adducts of aliphatic C12-18 alcohols, but preferably less than about one eighth of the amount of said fatty acid;
(c) optionally, from about 0.1% to about 4% by weight of organic polycarboxylic acid, preferably citric acid;
(d) optionally, up to about 0.2% by weight of base-stable anionic surfactant such as the alkali or alkaline earth salts of dodecylbenzene sulfonate;
(e) optionally, toxicologically-acceptable basic buffer such as potassium and/or sodium basic materials, e.g., the hydroxides and/or salts of carbonate and/or bicarbonate;
(f) optionally, toxicologically-acceptable preservative;
(g) optionally, but preferably, from about 0.05% to about 10%, preferably from about 0.1% to about 5%, more preferably from about 0.3% to about 2% of phosphoric acid;
(h) optionally, at least about 0.05%, preferably from about 0.1% to about 10%, most preferably from about 0.25% to about 3.0%, by weight, of water-soluble polyethylene glycol having a molecular weight of about 200, or higher; and
(i) the balance comprising an aqueous carrier selected from water and, optionally, low molecular weight, toxicologically-acceptable organic solvent such as ethanol, glycerol, etc.;
all of the acidic materials above being, of course, neutralized under the alkaline conditions of the product, preferably neutralized with sodium and/or potassium, preferably potassium, compatible basic material, wherein said aqueous solution has a pH in the range of 9.5 or greater, preferably more than about 11, and even more preferably from about 11.5 to about 12.5, and said composition preferably being essentially free of any material that is not toxicologically acceptable.
The inventions disclosed herein preferably encompass compositions for use in a method for cleaning fruits and vegetables at a basic pH above about 9.5, comprising:
(a) from about 0.01% to about 15% of C8-C18 fatty acid which is neutralized, preferably a member selected from the group consisting of sodium or potassium oleate (preferred), or from about 0.5% to 10% by weight of sodium or potassium laurate;
(b) optionally, from about 0.1% to about 4% by weight of nonionic surfactant, especially ethoxylated/propoxylated adducts of aliphatic C12-18 alcohols, but preferably less than about one eighth of the amount of said fatty acid;
(c) optionally, but preferably, from about 0.2% to about 4% by weight of potassium and/or sodium polycarboxylate, having detergent building capability and preferably being derived from natural sources, such as potassium and/or sodium citrate, as a dispersant for particulate soils;
(d) optionally, up to about 0.2% by weight of base-stable anionic surfactant such as the alkali or alkaline earth salts of dodecylbenzene sulfonate;
(e) optionally, toxicologically-acceptable basic buffer such as potassium and/or sodium basic materials, e.g., the hydroxides and/or salts of carbonate and/or bicarbonate;
(f) optionally, toxicologically-acceptable preservative;
(g) optionally, but preferably, from about 0.05% to about 10%, preferably from about 0.1% to about 5%, more preferably from about 0.3% to about 2% of phosphoric acid; and
(h) optionally, at least about 0.05%, preferably from about 0.1% to about 10%, most preferably from about 0.25% to about 3.0%, by weight, of water-soluble polyethylene glycol having a molecular weight of about 200, or higher;
(i) the balance preferably comprising aqueous carrier selected from water and, optionally, low molecular weight, toxicologically-acceptable organic solvent such as ethanol, glycerol, etc., preferably selected from water and water-ethanol;
wherein said aqueous cleaning solution has a pH of 9.5 or greater, and preferably employs carbonate salt, or salts, as buffer (e), preferably with hydroxide base, to provide a pH of from about 11 to about 12.5, more preferably from about 11.5 to about 12.5. The compositions can also be formulated as concentrates, in which at least part of (i) is removed and the levels of the remaining ingredients are adjusted to complete the formula. In all of the above lists of components, if an ingredient can be classified in more than one place, it will be classified in the first place it can appear.
A more specific method for cleaning fruits and vegetables at a basic pH, preferably more than about 9.5, comprises contacting the surfaces of said fruits and vegetables with an aqueous cleaning solution comprising potassium oleate, preferably at a level of more than about 0.5%. Potassium oleate is mild, rinses well, has minimal odor, is effective in removing unwanted materials, especially wax, from apples, does not oversuds, and is very safe, even when the composition is misused and the vegetable, or fruit, etc., is not completely rinsed. Therefore, it is a uniquely preferred surfactant for use in cleaning food materials like vegetables and fruits. The potassium cation is more useful than the sodium cation, especially in the absence of polyethylene glycol, since the potassium oleate is quite soluble whereas the sodium oleate tends to form a less soluble soap, especially at low temperatures.
A concentrated, alkaline method for cleaning produce comprises contacting the surfaces of produce with a cleaning solution containing from about 0.5% to about 15%, preferably from about 0.75% to about 8%, more preferably from about 1% to about 5%, detergent surfactant, preferably one that is GRAS, and more preferably said oleate surfactant, said cleaning solution having a pH of from about 9.5 to about 12.5, preferably from about 11 to about 12.5, especially when the detergent surfactant is a soap such as the said oleate, more preferably from about 11.5 to about 12.3. Such compositions when used in an effective amount to clean apples coated with wax, will provide more effective removal of the wax when combined with the neutralized phosphoric acid. Removal of wax from apples is one of the most difficult cleaning tasks and therefore is indicative of overall superior performance. It is important to remove as much wax as possible to minimize the amount of any undesirable materials that may be trapped by the wax.
Another preferred variation in the above methods for cleaning produce involves placing said cleaning solutions in a spray container to provide a spray of said solution to distribute the said solution, or solutions, over the surfaces of the produce while utilizing only a minimum amount of the cleaning solution and minimizing the exposure of the remaining solution to the atmosphere, where the solution is more likely to be contaminated and/or exposed to oxygen, both of which tend to cause undesirable changes in the solutions from aesthetic and/or performance considerations. In such spray processes, there is only need for a relatively small amount of material in the package, and for individual consumer use, this is desirable, since some consumers will not be able to manipulate large weights. For individual consumer usage, typically, the container will contain no more than about two gallons (about eight liters), preferably no more than about one gallon (about four liters), especially when the container is a spray container, even one that has a tube that permits the spray device to be manipulated while the bulk container remains in place. More preferably such spray containers contain about one liter, or less, of cleaning solution.
The invention encompasses basic cleaning compositions in both concentrated and dilute forms, especially adapted for practicing said methods. (In the following disclosure, the lower amounts of the specified ingredients denote the dilute forms of the compositions herein and the higher amounts denote the concentrated forms which are typically diluted by a factor of from about 2 to about 3.) The compositions can be concentrated even more to non-aqueous liquids or solids according to the teaching in U.S. Pat. No. 5,280,042, Lopes, said patent being incorporated by reference. Such compositions include the following.
A composition for cleaning fruits and vegetables at a basic pH, comprising:
(a) from about 0.1% to about 15%, preferably from about 1% to about 5%, by weight of a member selected from the group consisting of sodium or potassium oleate (preferred), sodium or potassium laurate, or mixtures thereof;
(b) optionally, from about 0.1% to about 4%, preferably about 0.3% to about 1.0%, by weight of nonionic surfactant as described above;
(c) from about 0.2% to about 4% by weight of polycarboxylic acid salt, especially potassium hydrogen citrate;
(d) from about 0.3% to about 5% of ortho-phosphoric acid; and
(e) the balance comprising aqueous carrier selected from water and water-ethanol;
wherein said composition has a pH of 9.5 or greater.
Preferably, the basic compositions herein contain from about 0.5% to about 1.5% by weight of potassium, and/or sodium, carbonate and/or bicarbonate buffer and have a pH of from about 11.5 to about 12.5.
Preferred compositions for use herein in a concentrated alkaline method contain from about 0.1% to about 15%, preferably from about 0.5% to about 8%, more preferably from about 1% to about 5%, detergent surfactant, preferably one that is GRAS; from about 0.3% to about 5% of ortho-phosphoric acid and have a pH of from about 9.5 to about 12.5, preferably from about 11.5 to about 12.3. Such compositions, when used in an effective amount to clean apples coated with wax, will provide more effective removal of the wax. Removal of wax from apples is one of the most difficult cleaning tasks and therefore is indicative of overall superior performance.
The present invention also encompasses detersive compositions with an improved tactile impression which are especially adapted for cleaning fruits and vegetables, comprising:
(a) at least about 0.1%, preferably from about 0.5% to about 8%, most preferably from about 1% to about 5%, by weight, of a C12-C18 fatty acid or salt thereof;
(b) at least about 0.05%, preferably from about 0.1% to about 10%, most preferably from about 0.25% to about 3.0%, by weight, of water-soluble polyethylene glycol having a molecular weight of about 200, or higher;
(c) from about 0.1% to about 5% of neutralized ortho-phosphoric acid; and
(d) water or water-ethanol fluid carrier, said composition having a basic pH.
The balance of the composition can comprise various optional adjunct materials, pH-adjusting agents, perfumes or essences, preservatives and the like.
In a preferred mode, component (b) has a molecular weight in the range from about 300 to about 9500.
Typical compositions herein are wherein component (a) is potassium oleate, and wherein the weight ratio of (a):(b) is in the range from about 1:2 to about 30:1, preferably from about 1:1 to about 15:1.
The compositions having improved tactile impression are typically formulated in the basic pH range, preferably from about pH 9.5 to about pH 12.5. Preferred compositions have a viscosity at room temperature of less than about 100 centipoise, preferably less than about 50 centipoise for sprayable compositions.
Preferred compositions for use herein contain only materials that are GRAS, including, of course, direct food additives affirmed as GRAS, to protect against possible misuse by the consumer. Traditionally, most suggestions for cleaning of fruits and/or vegetables have contemplated a commercial scale where there is typically more control over the conditions, especially the amount and thoroughness of rinsing. The present invention, especially the methods involving use of hand held trigger activated spray means are primarily/solely suitable for use by individual consumers so that it is essential that extra safety be built into the product. Failure to rinse thoroughly after cleaning is less of a concern if all of the ingredients are GRAS. This is especially important when concentrated basic compositions suitable for removal of wax from apples are used. The larger amounts of materials needed for removal of wax create an heretofore unknown level of risk for the individual consumers, many of whom are not likely to read, or follow, instructions which would permit safe use of non-GRAS materials.
The ingredients in the above compositions are preferably selected and used in proportions which provide substantially clear compositions. xe2x80x9cSubstantially clearxe2x80x9d includes only minimal haziness, and preferably the compositions are completely clear. The ingredients are also selected to have minimal odor, both initially and after storage. The lack of odor is especially important in compositions for use on food. The compositions preferably have a viscosity that is more than about 2 centipoise, preferably more than about 10 centipoise when at rest, but thin under shear to permit easy dispensing, especially from spray containers.
Below pH about 9.7, the compositions can exhibit some objectionable fatty acid odor. Even at the optimal pH""s above 11, some odor can persist. In order to mask this odor, the compositions can contain a GRAS perfume, or essence, ingredient. Especially preferred for this use are oils derived from citrus fruit, e.g., oranges, lemons, limes, grapefruits, tangerines, tangelos, etc. which contain relatively large amounts of terpenes.
All documents cited herein are incorporated herein by reference.